On Tue, 20 Oct 2015, Richard Biener wrote:

On Tue, Oct 20, 2015 at 8:46 AM, Hurugalawadi, Naveen
<naveen.hurugalaw...@caviumnetworks.com> wrote:
Hi,

+/* Fold X + (X / CST) * -CST to X % CST.  */
This one is still wrong
Removed.

I don't understand the point of the FLOAT_TYPE_P check.
The check was there in fold-const. So, just had the same check.

Will we also simplify (A & B) - (A & ~B) into B - (A ^ B) ?
Done.

or maybe integer_all_onesp (const_binop (BIT_XOR_EXPR, type, @2, @1))
Done.

:c on bit_ior? It should also allow you to merge the 2 CST versions into one.
Had it. But due to the error on "logical_inverted_value"; confused it with
this pattern and had duplicated it.

I am not really in favor of the indentation change (or the comment).
Done.

This patch is ok when bootstrapped / tested and with a proper changelog entry.
Regression tested on X86_64 with no extra failures.

+(simplify
+ (minus (bit_and:s @0 INTEGER_CST@2) (bit_and:s @0 INTEGER_CST@1))
+ (if (integer_all_onesp (const_binop (BIT_XOR_EXPR, type, @2, @1)))
+  (minus (bit_xor @0 @1) @1)))

use if (wi::bit_and (@2, @1) == 0)

I believe the original transformation required @1 and @2 to be bit_not
of each other, so this might not work. He had a suitable test using wi,
it is my fault he changed it (sorry for not being clear enough that my
remark wasn't meant as a patch). The reason was so we could change
INTEGER_CST to CONSTANT_CLASS_P and handle vectors.

and instead of the 2nd group

+/* Fold (A & B) - (A & ~B) into B - (A ^ B).  */
+(simplify
+ (minus (bit_and:s @0 @1) (bit_and:s @0 (bit_not @1)))
+  (minus @1 (bit_xor @0 @1)))
+(simplify
+ (minus (bit_and:s @0 INTEGER_CST@1) (bit_and:s @0 INTEGER_CST@2))
+ (if (integer_all_onesp (const_binop (BIT_XOR_EXPR, type, @2, @1)))
+  (minus @1 (bit_xor @0 @1))))

place a :c on the minus of the one not matching INTEGER_CSTs.

Will that really work?

--
Marc Glisse

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